What modem do you have? Which Xfinity router? Or do you have a combined modem/router?
Connectivity being:
ISP (Xfinity) === (Coax)===> Modem [LAN port] ---- Ethernet cable ---> [WAN port] Router [LAN ports] --- Ethernet ---> wired devices and ~~~ Wireless ~~~> wireless devices.
Feel free to edit and correct my line diagram as necessary.
Do you have any Windows devices in the network? If so, run "ipconfig /all"(without quotes) via the Command Prompt and post the results.
Here is the ipconfig on my MacBook:
Last login: Mon Aug 1 19:02:46 on console
[Moderator edit to remove personal information] @JohnS-MacBook-Air ~ % ifconfig -a
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
options=1203<RXCSUM,TXCSUM,TXSTATUS,SW_TIMESTAMP>
inet 127.0.0.1 netmask 0xff000000
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
nd6 options=201<PERFORMNUD,DAD>
gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
anpi1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether 1e:80:30:1a:f8:66
inet6 fe80::1c80:30ff:fe1a:f866%anpi1 prefixlen 64 scopeid 0x4
nd6 options=201<PERFORMNUD,DAD>
media: none
status: inactive
anpi0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether 1e:80:30:1a:f8:65
inet6 fe80::1c80:30ff:fe1a:f865%anpi0 prefixlen 64 scopeid 0x5
nd6 options=201<PERFORMNUD,DAD>
media: none
status: inactive
en3: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether 1e:80:30:1a:f8:45
nd6 options=201<PERFORMNUD,DAD>
media: none
status: inactive
en4: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether 1e:80:30:1a:f8:46
nd6 options=201<PERFORMNUD,DAD>
media: none
status: inactive
en1: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
options=460<TSO4,TSO6,CHANNEL_IO>
ether 36:54:22:d7:1c:00
media: autoselect <full-duplex>
status: inactive
en2: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
options=460<TSO4,TSO6,CHANNEL_IO>
ether 36:54:22:d7:1c:04
media: autoselect <full-duplex>
status: inactive
bridge0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=63<RXCSUM,TXCSUM,TSO4,TSO6>
ether 36:54:22:d7:1c:00
Configuration:
id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
ipfilter disabled flags 0x0
member: en1 flags=3<LEARNING,DISCOVER>
ifmaxaddr 0 port 8 priority 0 path cost 0
member: en2 flags=3<LEARNING,DISCOVER>
ifmaxaddr 0 port 9 priority 0 path cost 0
nd6 options=201<PERFORMNUD,DAD>
media: <unknown type>
status: inactive
ap1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether 3e:a6:f6:1f:9a:46
nd6 options=201<PERFORMNUD,DAD>
media: autoselect
status: inactive
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether 3c:a6:f6:1f:9a:46
inet6 2601:c6:4180:1a20::90b prefixlen 64 dynamic
inet6 fe80::1cda:3c4f:b4e0:3d39%en0 prefixlen 64 secured scopeid 0xc
inet6 2601:c6:4180:1a20:c19:8140:c22e:5ecd prefixlen 64 autoconf secured
inet6 2601:c6:4180:1a20:7878:d236:2c90:8c02 prefixlen 64 autoconf temporary
inet6 2601:c6:4180:1a20::8519 prefixlen 64 dynamic
inet 10.0.0.82 netmask 0xffffff00 broadcast 10.0.0.255
nd6 options=201<PERFORMNUD,DAD>
media: autoselect
status: active
awdl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether b2:b6:12:53:bd:89
inet6 fe80::b0b6:12ff:fe53:bd89%awdl0 prefixlen 64 scopeid 0xd
nd6 options=201<PERFORMNUD,DAD>
media: autoselect
status: active
llw0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=400<CHANNEL_IO>
ether b2:b6:12:53:bd:89
inet6 fe80::b0b6:12ff:fe53:bd89%llw0 prefixlen 64 scopeid 0xe
nd6 options=201<PERFORMNUD,DAD>
media: autoselect
status: active
utun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1380
inet6 fe80::809f:b580:ad46:85da%utun0 prefixlen 64 scopeid 0xf
nd6 options=201<PERFORMNUD,DAD>
utun1: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 2000
inet6 fe80::1c9f:11eb:2fb9:da79%utun1 prefixlen 64 scopeid 0x10
nd6 options=201<PERFORMNUD,DAD>
[Moderator edit to remove personal information]@JohnS-MacBook-Air ~ %